The present invention relates generally to a vehicle suspension system. More specifically, the present invention relates to a composite spring and method of manufacturing such a spring that functions as a lower control arm while simultaneously serving as the coil spring, stabilizer bar and shock absorber in a suspension system.
Springs, and more specifically, leaf and coil springs, are used to form a portion of a suspension system used to suspend a vehicle""s running gear from the vehicle""s frame and to provide stability to the vehicle as it is subjected to compression, tension, torsion and bending forces during operation.
It is well known in the art to form composite leaf springs for use as a spring and/or control arm in a vehicle suspension system. The composition of the leaf spring varies with the location of the suspension system. Generally, multi-leaf springs formed of a plurality of metal leaves and rubber disposed between the leaves are used for rear suspensions while coil springs, as stated above, are used for a vehicles"" front suspension. More recently, composite leaf springs constructed of glass fiber in an epoxy matrix have been developed to replace steel leaf and coil springs in production passenger cars. Examples of these springs and a method for making the same may be found in U.S. Pat. No. 3,968,958 issued Jul. 13, 1976 to Huchette et al. and entitled xe2x80x9cComposite Material Springs and Manufacture;xe2x80x9d U.S. Pat. No. 4,611,793 issued Sep. 16, 1986 to Nishiyama et al. and entitled xe2x80x9cLeaf Spring Assembly for Wheel Suspension;xe2x80x9d U.S. Pat. No. 4,659,071 issued Apr. 21, 1987 to Woltron and entitled xe2x80x9cProcess for Producing a Plastic Leaf Spring, as well as a Plastic Leaf Spring Appropriately Manufactured According to this Process;xe2x80x9d U.S. Pat. No. 4,771,997 issued Sep. 20, 1988 to Haldenwanger et al. and entitled xe2x80x9cMotor Vehicle Fiber-Reinforced Synthetic Material Leaf Spring or Transverse Link with End Clamp/Power-Induction Unit;xe2x80x9d U.S. Pat. No. 4,772,044 issued Sep. 20, 1988 to Booher and entitled xe2x80x9cVehicle Suspension System with Flexible Control Arm;xe2x80x9d U.S. Pat. No. 4,969,633 issued Nov. 13, 1990 to Ryan and entitled xe2x80x9cMolded Fiber Reinforced Plastic Leaf Spring;xe2x80x9d U.S. Pat. No. 5,016,861 issued May 21, 1991 to Thompson et al. and entitled xe2x80x9cMounting of a Single Transverse Leaf Spring for Vehicles;xe2x80x9d U.S. Pat. No. 5,118,373 issued Jun. 2, 1992 to Krummenacher and entitled xe2x80x9cMethod of Winding Fiber Material to Form a Leaf Spring;xe2x80x9d U.S. Pat. No. 5,425,829 issued Jun. 20, 1995 to Chang and entitled xe2x80x9cMethod of Manufacturing Hybrid Composite Leaf Springs;xe2x80x9d along with many foreign patents and publications.
None of the above-described patents disclose the use of a composite spring that includes dimensional integrity and flexibility as part of a suspension system for automotive vehicles. The apparatus and method of making the apparatus of the present invention includes both dimensional integrity and flexibility in a single element. The composite spring of the present invention replaces the control arm, spring and stabilizer bar in a conventional suspension system and additionally, the shock absorber in an active suspension system.
It is, therefore, the object of the present invention to provide an improved vehicle suspension system.
It is another object of the present invention to provide a composite spring for use in a vehicle suspension system where the composite spring replaces the lower control arm, the stabilizer bar and the coil spring in a standard vehicle suspension system.
It is another object of the present invention to provide a composite spring for use in a vehicle suspension system where the composite spring replaces the lower control arm, the stabilizer bar, the coil spring and the shock absorber in an active vehicle suspension system.
It is further an object of the present invention to provide a method far making a composite spring for use in a vehicle suspension system that is formed of both carbon and glass fibers and having a sinusoidal profile transversely mounted about the vehicle frame.
In a preferred embodiment of the present invention, a flexible, resilient composite spring is pivotally connected to the vehicle wheel assembly by standard means such as a ball joint and knuckle. The composite spring is formed having a sinusoidal profile with rectangular cross-section preferably spanning transversely between parallel vehicle wheel assemblies. The composite spring is pivotally connected to the parallel vehicle frames by opposing perpendicular brackets welded to an upper and lower portion of the vehicle frame. A rubber bushing is preferably provided within each bracket and is in contact with opposing sides of the composite spring, allowing the spring to pivot between the vehicle frame.
The composite spring of the present invention is preferably formed with carbon and glass fibers. The sinusoidal composite spring blank is preferably molded with a neutral axis extending along the length of the spring at a midpoint of the sinusoidal profile. The blank preferably is formed with carbon fibers extending at and below the neutral axis surrounded by glass fibers, both fibers preferably impregnated with a hardening substance. The carbon fibers arc successfully located at and below the neutral axis of the blank by pre-loading the mold frame in tension before placing the frame in the mold. Location of the carbon fibers in this manner provides a stronger, more durable composite spring for both a standard and active suspension system.